Method of making a heat exchanger from particulate material



7 1 4 t 4 e m 4 S 9 v n6 t e 3 B h S w 2 R F R E G N AL HA CI E EE Y m TAM AE H V T AA m 6 ENG July 30, 1968 METHOD OF MAKI PAR'II OriginalFiled Aug. 24. 1965 I III/ III] II I 1111 INVENTOR EMERYZ WILY/ ATTORNEYJuly 30, 1968 E. VALYI METHOD OF MAKING A HEAT EXCHANGER FROMPARTICULATE MATERIAL Original Filed Aug. 24, 1965 2 Sheets-Sheet 2 FIG-7FIG-8 ilfllllll u .r

INVENTOR. E ME RY! I44LY/ FIG-6 ATTORNEY United States Patent 3,394,447METHOD OF MAKING A HEAT EXCHANGER FROM PARTICULATE MATERIAL Emery I.Valyi, Riverdale, N.Y., assignor to Olin Mathieson Chemical Corporation,a corporation of Virginia Original application Aug. 24, 1965, Ser. No.482,242. Divided and this application May 2, 1967, Ser. No.

1 Claim. (Cl. 29157.3)

ABSTRACT OF THE DISCLOSURE This invention relates generally to heatexchangers, and more particularly to a novel heat exchanger having abody of pervious material therein, and to the method of producing such aheat exchanger.

This application is a division of co pending application Ser. No.482,242, filed Aug. 24, 1965, now abandoned.

As is known in the heat exchange art, the greatest heat exchange isachieved by providing the maximum possible area of heat exchange surfaceacross which the desired heat exchange may take place. Various deviceshave been employed to so increase the area such as. for example, fins orcorrugations across which pass the media between which the heat exchangeis to take place. However, it has been found that greatly increased heattransfer surfaces can be achieved by instead employing a body ofpervious material, or a porous body having interconnected voids,conductively joined to a solid metal member. Such a body of perviousmaterial presents a large exposed surface area for heat exchangepurposes combined with the high heat conductivity of the solid member,as well as other advantages to be discussed shortly.

By the instant invention there is provided a heat exchanger having aunique configuration and arrangement of such a pervious body within aheat exchanger resulting in greatly increased heat exchange properties.The concept of the instant invention may be employed in heat exchangersof any desired shape, but is particularly adapted to tubular heatexchangers. As known in the art, the use of heat exchangers of a tubularconfiguration is highly advantageous in certain environments where it isdesired that the heat exchange take place wholly within the exchanger.The tubular heat exchangers commonly in use in such an environment areof the type known in the art as shell and tube, wherein a plurality oftubes conveying one heat exchange medium are arranged within a shellthrough which is circulated another heat exchange medium, with orwithout the use of baffles to direct the flow, which is substantiallyaxial along the tubes.

In the concept of the instant invention there is provided a heatexchanger in which not only the heat exchange area is increased but theflow of one of the media is directed in a plurality of passages betweena series of pervious bodies through which flow the second medium. Theadvantages resulting from such a flow are achieved by the provision of aplurality of spaced-apart pervious bodies within a formed strip. By aparticular construction of the strip and the pervious bodies, to bediscussed hereinafter, space is provided within the heat exchanger toserve as guide channels for each of the heat exchange media resulting inthe desired flow.

It is accordingly an object of this invention to provide a heatexchanger which is compact and yet capable of high efiiciency and lowpressure drop.

It is a further object of this invention to provide such a heatexchanger having bodies of pervious material joined therein by ametallic bond.

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It is a still further object to provide a novel method of producing suchheat exchangers.

Additional objects and advantages will become apparent to those skilledin the art from a consideration of the details of several specificembodiments illustrated in the drawings, in which:

FIGURE 1 is a perspective view of a heat exchanger embodying theconcepts of this invention;

FIGURE 2 is an axial cross-section of the heat exchanger of FIGURE 1,taken along the line IIII thereof;

FIGURE 3 is a longitudinal cross-section of the heat exchanger of FIGURE1, taken along the lines lII-IlI of FIGURE 2;

FIGURE 4 is a frontal view of one of the header plates employed in theheat exchanger of FIGURE 1;

FIGURE 5 is a frontal view of a second header plate employed in the heatexchanger of FIGURE 1;

FIGURE 6 is an exploded view of a portion of a first modification of theinstant invention;

FIGURE 7 is an exploded view of a portion of a second modification ofthe instant invention; and

FIGURE 8 is a cross-sectional view similar to FIG- URE 2, illustrating afurther modification of the heat ex changer of FIGURE 1.

An exemplary heat exchanger according to this invention is shown inFIGURE 1, and is designated generally by 10. A first heat exchangemedium, for example the medium to be employed in heating or cooling, isintroduced into the heat exchanger 10 at one end thereof, as shown bythe arrow 11, and exits from the opposite end thereof in the directionof the arrow 12. A second heat exchange medium, for example the mediumto be cooled or heated, enters the heat exchanger 10 through anysuitable fitting in the direction of the arrow 13, is circulated throughthe heat exchanger, and exits through a suitable fitting in thedirection of the arrow 14. It will be obvious that any desired mediamight be employed in the instant heat exchanger; for example, the mediumintroduced at 11 may be water, and that introduced at 13 may be oil.

The construction of the heat exchanger 10 is shown in detail in FIGURES2 and 3. Referring first to FIG- URE 2, it may be seen that the heatexchanger 10 comprises a tube 15 in which there may be situated a metalstrip 16. folded as shown in FIGURE 2 to provide a plurality of cavities17 and passages 18, for reasons to become evident shortly. The foldedmetal strip may be secured within the tube in any desired method, as bybrazing throughout its entire length along the edges indicated at 19 and20. As can be seen in FIGURE 3. the strip 16 extends along substantiallythe full length of tube 15.

Within each of the cavities 17 there is situated in heat transferrelationship with the strip 16 a pervious body 22. It will be seen thatthe pervious body 22 occupies all of the cavity 17 in which it iscontained except for a void 23 at one end thereof, for reasons also tobecome evident shortly. It will also be noted that the strip 16 may restupon the tube 15 at edges 24 and 25 opposed to the attached edges 19 and20. These ends 24 and 25 need not be attached to the tube 15.

Referring now to FIGURE 3 of the drawings. the function of the structurepreviously described will be appreciated. A first heat exchange mediummay flow through the tube 15 in the direction of the dashed line arrows30, it being evident that any desired fittings may be employed atopposed ends of the tube 15. The How of this first heat exchange mediumis restricted to the open space 31 above the metal strip 16, see FIGURE2. and to the passages 18. Entry into the cavities 17 is prevented byheader plates 32 and 33 at opposed ends of strip 16, to be described indetail shortly.

Considering now the flow of the second heat exchange medium, it will beseen in FIGURE 2 that such medium is introduced into the heat exchangerthrough a suitable opening 34 in the wall of tube 15, and exits througha similar opening 35. The medium enters through opening 34 and, flowingin the direction of the solid line arrows 36, disperses throughout aspace 37 below the cavities 17, thence through the cavities 17collecting at the upper ends 23 thereof, thence out through the outletopening 35. To expedite the flow of this medium from the heat exchanger,a header plate 38, to be described in detail shortly, is provided toform a manifold space 39 for collecting the medium flowing from thevoids 23. Any desired fittings may of course be provided at openings 34and 35 for external flow of the second heat exchange medium.

Referring now to FIGURES 4 and 5, the specific construction of theheader plates will be seen. FIGURE 4 illustrates the construction of theheader plate 32; header plate 33 is identical in construction and itwill be evident that all description of header plate 32 is equallyapplicable to the header plate 33. The header plate 32 consists of anon-pervious sheet having a solid portion 40 around a portion of theperiphery thereof and a plurality of projecting teeth 41 centrallythereof. Referring momentarily to FIGURE 2, it will be evident that thesolid portion 40 and projecting teeth 41 are of a configuration to sealOff all of the area within tube other than the passages 18 and space 31.

Referring now to FIGURE 5, the header plate 38 is similar to the headerplate 32 except that the projecting teeth 42 here terminate short of theupper ends of the cavities 17, see FIGURE 2. It will be evident thatthis construction seals off all of the area within the tube 15 otherthan passages 18, space 31, and the voids 23 at the upper ends ofchannels 17. The width of the teeth 42 may be so dimensioned as to beclosely received within channels 17; slits 43 and 44 are provided toreceive the outermost edges of strip 16. Alternatively, the area ofheader plate 38 to the left of slit 43 and to the right of slit 44-andthe corresponding areas of header plates 32may be deleted so that thespaces to the left and right of strip 16 may also be employed for flowof a heat exchange medium. It is to be understood that the header plate38 illustrated is only one means of preventing flow of the heat exchangemedium passing through the pervious bodies 22 directly into the channel39. Thus, any means of sealing off the areas of the pervious bodiesillustrated to be in contact with the header plate 38 will sutfice. Forexample, a suitable resinous sealing compound may be applied to suchareas.

Referring again to FIGURE 3, it will be seen that the header plates justdescribed assure the desired How of the heat exchange media. Headerplate 32 seals off the strip 16 except at the passages 18, thus forcingthe heat exchange medium 15 to flow through the passages 18 and in theupper space 31. Header plate 33 serves a similar function in sealing offthe opposite end of the strip 16. Header plate 38 serves to seal off thecavities 17 except at the upper portions thereof, thus assuring that theheat exchange medium flowing through thhe pervious bodies 22 will have aready path for exit from the heat exchanger.

By the flow indicated, the heat exchange advantages obtained will beappreciated. By virtue of the plurality of passages through the strip 16the two heat exchange media are in heat exchange relationship along agreatly increased surface area. Additionally, the heat exchange mediaflowing through the pervious bodies 22 is exposed to a materiallyincreased area for heat exchange by virtue of the multitudinous pathswhich the heat exchange medium must take in passing through the perviousbodies. As will be indicated shortly, the pervious bodies are in heatexchange relationship with the cavities and accordingly also in heatexchange relationship with the medium flowing through the passagesbetween the cavities.

The form of the strip 16 illustrated in FIGURE 2 is merely exemplary, itbeing evident that the cross-section thereof may be altered as desired.Two modifications which have been found to be especially advantageousare illustrated in FIGURES 6 and 7 of the drawings, which are explodedportions of strips analogous to strip 16 of FIGURE 2, illustrating onepassage between two cavities containing pervious bodies 22. By theparticular construction of the modified channels 18' and 18", the heattransfer may be materially increased while providing additional rigidityto the walls of the channels. As shown for example in FIGURE 6, thechannel 18' may be divided into two parts by providing an indentation ineach side of the passage wall 18, as by embossing, resulting in an upperpassage 51 and a lower passage 52.

Similarly, a greater number of divisions of the passage 18 may beaffected by providing in the walls of the passage 18 a greater number ofindentations 55, see FIG- URE 7. These indentations may be easilyachieved, as by any standard corrugating procedure of the strip 16 priorto bending it in the shape illustrated.

It will be evident that either of the modifications just discussed mayrequire modification of the header plates to conform to thecross-section of the strip. Alternatively, the embossments orcorrugations may be interrupted in the areas where the header plates areto be applied.

As indicated hereinbefore, the application of this invention to atubular heat exchanger is merely exemplary. Thus, the strip 16 may besuitably modified to form a unitary heat exchanger apart from anysurrounding tube, and employed for example by simple immersion in anysuitable container. This application is illustrated in FIG- URE 8,wherein it will be seen that structure analogous to structure of thestrip of FIGURE 2 is indicated by the same reference character primed.Thus, the strip 16 is formed with a plurality of cavities 17' andpassages 18', with pervious bodies 22' and voids 23' situated in thecavities 17'. Here, however, the outermost side walls of the strip 16'are extended downwardly, as at and 61, bent inwardly, as at 62 and 63,and joined together in any suitable manner, as at 64. The perviousbodies 22' may be discrete, or they may be joined together, as at 65. Ata lower portion of the strip 16, a large void 66 is formed to distributethe heat exchange medium in the same manner as the space 37 of FIGURE 2.

It will be evident that provision of suitable openings in the lower endof the strip 16', analogous to openings 34 and 35 in FIGURE 3, andaddition of appropriate manifolds, analogous to 32, 33 and 38 in FIGURE3, will allow for circulation of a heat exchange medium in the samemanner as described hereinbefore. The resulting heat exchanger may thenbe used alone, or in assembly with other similar modules, as byimmersion in the second heat exchange medium.

Considering now the manner in which a heat exchanger according to thisinvention may be produced, production of the heat exchanger of FIGURE 1will be taken as exemplary, it being understood that suitablemodification of the steps indicated will result in the modifications ofFIG- URES 6, 7 and 8. It is to be noted that various combinations ofmetals may be utilized in forming the heat exchangers according to theinstant invention; and accordingly the solid portions and the perviousbody may be of the same metal or alloy, or the pervious structure andthe solid member may be comprised of different compositions. Forexample, both the pervious body and solid portions may be formed of thesame stainless steels, coppers, brasses, carbon steels, aluminums orvarious combinations thereof. As will be evident, the ultimate use ofthe resultant structure determines the specific combination of alloys tobe employed.

The pervious bodies may be produced by a process wherein particles,usually spherical, are poured by gravity into an appropriately shapedconfined space and usually vibrated to cause the particles to compactuniformly. As is obvious, the choice of particle size will largelydetermine the size of openings in the resulting pervious bodies. Thebodies of particles so packed are then treated in accordance with any ofthe well known metallurgy practicese.g., sintering, welding, brazing orsoldering employing an appropriate coating-to produce in each body ametallic bond between the particles. Thus, there is provided perviousbodies whose bulk density, or apparent density, is but a fraction of thedensity of the metal or alloy from which the particles are obtained.Furthermore, such process result in a metallic bond between the perviousbodies and solid material around the bodies.

Thus, the particles may be poured into the formed strip 16 and joined inplace by any of the metallury practices noted above. A particularlyadvantageous method of forming the voids 23 is to pour the particlesinto the formed strip 16, with the header plates 32 and 38 in place.While the assembly is oriented in a position rotated 180 from theposition shown in FIGURE 2. The volume of particles poured into each ofthe cavities 17 may be so calculated that when the strip 16 is returnedto the position shown in FIGURE 2 the desired voids 23 at the upper endsof cavities 17 are achieved. The resulting body may then bemetallurgically treated, resulting in a. metallic bond (1) between thevarious particles of each of the bodies 22, (2) between each of thebodies 22 and the walls of the cavities 17 in which they are positioned,(3) between each of the bodies 22 and the header plates 32 and 38, and(4) between the strip 16 and the header plates 32 and 38. Header plate33 may then be similarly attached.

The resulting assembly may, if so desired, then be inserted into thetube 15 and joined in place, While it is shown in FIGURE 2 that thelower edges 24 and 25 rest upon the interior walls of the tube 15, thisis not required and these lower ends may be spaced from the wall it sodesired. Similarly, the resulting assembly may be one of a number ofsimilar modules put together within a single conduit, such as a largertube, to achieve greater heat exchange capacity. This may be done byjoining a number of modules in side-by-side relationship, or byorienting one such module atop the other. In the latter expedient, twomodules may be brought together with their ends having the voids 23 incontact, such that the passages 18 of each are in communication. Thevoids 23 of each may remain separate from the voids 23 of the other, orcorresponding voids 23 may be joined as by providing an opening in theupper wall of each of the cavities 17.

As will be obvious to those skilled in the art, the indicated flow ofthe heat exchanger media achieved by the instant device attains a highdegree of heat exchange with a minimum of pressure drop. The mediumwithin the pervious bodies distributes over the entire perviousstructure in a uniform manner over a greatly increased heat exchangesurface. The construction of the pervious bodies will be dictated by thecontemplated use of the exchanger dependent upon such factors as thethermal conductivity, specific heat, viscosity, and corrosive nature ofthe fluid, the presence of clogging solids in the fluid, and tolerablepressure drops.

It is to be understood that the concept of this invention need not belimited to the particular configurations indicated above. For example, atube need not be exclusively employed; any desired shape of exchangermay be provided, with the inner structure shaped accordingly to fit.Furthermore, the strip may be of any desired cross-section, any numberof heat exchange media may be employed, the exchanger may be used foreither heating or cooling, and the direction of flow of the heatexchange media may take a variety of patterns. While the flow directionsindicated above have been found to be the most desirable, the directionof flow of either or both of the heat exchange media may be reversed ifso desired. Additionally, the heat exchange media may be either liquidor gaseous, and thus the instant structure may serve as a liquid toliquid heat exchanger, a condenser, or an evaporator.

While several specific embodiments of this invention have been shown anddescribed, they are to be understood as for the purpose of illustrationonly and that various changes and modifications may be made in thedisclosed articles and method without departing from the spirit andscope of the invention as set forth in the appended claim.

What is claimed is:

1. The method of producing a heat exchanger of the type described, thesteps comprising (A) providing a strip formed to contain at least onecavity capable of containing particulate material, said cavity beingclosed at one end,

(B) filling said cavity with particulate material of a quantity lessthan the volume of said cavity,

(C) inverting said strip to achieve a void in the closed end of saidcavity, and

(D) creating a metallic bond between the particulate material and thewalls of said cavity.

References Cited UNITED STATES PATENTS 2,401,797 6/1946 Rasmussen.2,448,315 8/1948 Kunzog. 3,289,756 12/1966 Jaeger 29157.3

JOHN F. CAMPBELL, Primary Examiner.

PAUL M. COHEN, Assistant Examiner.

